Transcript Clotting with CVVH vs CVVHD (Mottes et al, CRRT 1999)

Complications of Pediatric CRRT
Theresa A. Mottes RN
Pediatric Dialysis/Research Nurse
C.S. Mott Children’s Hospital
University of Michigan
Complications of Pediatric CRRT
 Temperature instability
 Hemodynamic instability
 Anticoagulation Risk
 Circuit/Access Complications
Factors effecting hemodynamics
 Patient Volume Status
• Ultrafiltration Rate
– patients hemodynamic
– typically vasopressor dependent
– patients intravascular volume
• Ultrafiltration Rate
– 1-2ml/kg/hour net ultrafiltration
– absolute necessity to control ultrafiltration
– error of accurate ultrafiltration monitoring
RESULTS
(Smoyer et al, CRRT 1997)
Trilogy Pump: Accuracy over Range of Flow Rates
4
Dialysate
3
Ultrafiltrate
% Error
2
1
0
-1
-2
-3
-4
0
100 200 300 400 500 600 700 800 900 1000
IV Pump Flow Rate (ml/hr)
Ccs/hr
Ultrafiltration accuracy
2.8 kg infant on PRISMA
100
90
80
70
60
50
40
30
20
10
0
Prescribed net U/F
Actual net U/F
1
2
3
4
Hour of Therapy
Prescription
BFR 30 mls/min
Dx FR 300 mls/hr
avg/4
hrs
Factors effecting hemodynamics
 What now?
• Hourly assessment of Intake and Output
• Hourly Ultrafiltration calculations
– adjusting for pump error
• Accurate measuring of Ultrafiltration
• Close monitoring of hemodynamics
• Accurate daily weight
Factors effecting hemodynamics
 Calculation for Pump Error
Factors effecting hemodynamics
 Vasopressor clearance
• Vasopressor agents all have in common a
small molecular weight and minimal protein
binding
– Epinephrine
– Norepinephrine
– Dopamine
– Dobutamine
Factors effecting hemodynamics
 Vasopressors
• Due to proximity of infusion
– be aware of infusing vasopressor agents in
immediate proximity to the “arterial” port of the
hemofiltration machine
– potential for recirculation
– effects delivery and clearance
Intravascular Blood Volume
 < 10 kg 80 ml/kg
• e.g. 8 kg infant = 640 ml intravascular volume
 > 10 kg 70 ml/kg
• e.g. 20 kg child has 1.4 liter intravascular
volumeBlood

Priming Hemofiltration Circuit
• Recommended when circuit volume > 10 % of
patients intravascular blood volume
Anticoagulation
 Heparin
 Citrate
 None
Circuit Complications
Circuit Clotting
•
•
•
•
Inability to ultrafiltrate desired amount
Increasing Access/Return Pressure
Inadequate clearances
Observe clotting in filter/ tubing
Clotting with CVVH vs CVVHD
(Mottes et al, CRRT 1999)
RRT
PreHF
HCT
Post HF Delta Hct
HCT
change
27%
44%
62%
Post-filter
Replacement
36%
46%
27%
CVVHD
32%
34%
6%
CVVH
Pre-filter
Replacement
CVVH
Flow Rates
 Blood
• 5-10 ml/kg/min keeping venous pressure
under 200 mm Hg
 Dialysate/Replacement fluid
• 2 liters/1.73 m2/hr
– (extrapolation of adult data)
Access Complications
 What is the correct access?
• One that works
In Flow Difficulties
 Obstruction or clot on the return line
• high intrathoracic pressure with HIFI
• up against the vessel wall
 Clamp on inflow
 Access kinked at skin site
 Consider reversing or changing access
Out Flow Difficulties
 Clamp on access/”arterial” line
 Inflow port up against vessel wall
 Patient “dry” eg with femoral site
 High of blood flow requirements based
upon flow ability of access
 Consider
• reverse flow, change access, decrease blood
flow rates